Polyurethane-based composition

A composition comprising:

• an —NCO component comprising:
• A. at least one polyurethane including at least two NCO end groups obtained by a polyaddition reaction:
• of a composition comprising at least one diisocyanate;
• and
• of a composition comprising at least one polyol;
• and
• B. at least one polyisocyanate comprising at least three isocyanate —NCO functions selected from the group consisting of biurets, isocyanurates, adducts of diisocyanates and of triols, and mixtures thereof;
• an —OH component comprising:
• at least two polyols P1 each having a number-average molecular mass strictly less than 500 g/mol, said polyols P1 being such that:
• at least one polyol P1 comprises at least four hydroxyl functions;
• and
• at least one polyol P1 comprising two hydroxyl functions;
• and
• at least one polyol P2 having a number-average molecular mass strictly greater than 1000 g/mol, and
• at least one rheological agent.

A composition comprising:

• an —NCO component comprising:
• A. at least one polyurethane including at least two NCO end groups obtained by a polyaddition reaction:
• of a composition comprising at least one diisocyanate;
• and
• of a composition comprising at least one polyol;
• and
• B. at least one polyisocyanate comprising at least three isocyanate —NCO functions selected from the group consisting of biurets, isocyanurates, adducts of diisocyanates and of triols, and mixtures thereof;
• an —OH component comprising:
• at least two polyols P1 each having a number-average molecular mass strictly less than 500 g/mol, said polyols P1 being such that:
• at least one polyol P1 comprises at least three hydroxyl functions;
• and
• at least one polyol P1 comprises at least two hydroxyl functions;
• and
• at least one polyol P2 having a number-average molecular mass strictly greater than 1000 g/mol, and
• at least one rheological agent, wherein the —NCO component comprises B) a mixture of polyisocyanates, each of said polyisocyanates of the mixture comprising at least three NCO functions, the mean NCO functionality of said mixture of polyisocyanates being greater than or equal to 3.